java.lang.NullPointerException

Question

Exception in thread "main" java.lang.NullPointerException
at com.f0802.friend.dao.imp.UsersDaoImp.addUsers(UsersDaoImp.java:11)
at com.f0802.friend.biz.UsersBizImp.addUsers(UsersBizImp.java:11)
at com.f0802.friend.test.UsersTest.addUsers(UsersTest.java:33)
at com.f0802.friend.test.UsersTest.main(UsersTest.java:13)类:
public class UsersTest { public static void main(String[] args) {
// TODO Auto-generated method stub
addUsers(); }
public static void addUsers() {
Users u=new Users();
u.setLoginName("admin");
u.setPassword("123456");
u.setName("小张");
u.setGradenumber(100);
UsersBizImp ubi=new UsersBizImp();
ubi.addUsers(u);
}
}

Answer 1

空指针错误，去UsersBizImp 里的addUsers方法里看看。

Answer 2

users的Hibernate配置:
<hibernate-mapping>
    <class name="com.f0802.friend.entity.Users" table="users" schema="dbo" catalog="friend">
        <id name="id" type="java.lang.Integer">
            <column name="id" />
            <generator class="native" />
        </id>
        <property name="name" type="java.lang.String">
            <column name="name" length="20" not-null="true" />
        </property>
        <property name="loginName" type="java.lang.String">
            <column name="loginName" length="20" not-null="true" />
        </property>
        <property name="password" type="java.lang.String">
            <column name="password" length="20" not-null="true" />
        </property>
        <property name="gradenumber" type="java.lang.Integer">
            <column name="gradenumber" not-null="true" />
        </property>
        <set name="topics" inverse="true" cascade="delete" >
            <key>
                <column name="uid" not-null="true" />
            </key>
            <one-to-many class="com.f0802.friend.entity.Topic" />
        </set>
        <set name="articleses" inverse="true" cascade="delete" >
            <key>
                <column name="authorId" not-null="true" />
            </key>
            <one-to-many class="com.f0802.friend.entity.Articles" />
        </set>
        <set name="usersgrades" inverse="true" cascade="delete" >
            <key>
                <column name="usersId" not-null="true" />
            </key>
            <one-to-many class="com.f0802.friend.entity.Usersgrade" />
        </set>
        <set name="replies" inverse="true" cascade="delete" >
            <key>
                <column name="uid" not-null="true" />
            </key>
            <one-to-many class="com.f0802.friend.entity.Reply" />
        </set>
        <set name="userInfos" inverse="true" cascade="delete" >
            <key>
                <column name="usersId" not-null="true" />
            </key>
            <one-to-many class="com.f0802.friend.entity.UserInfo" />
        </set>
        <set name="messageses" inverse="true" cascade="delete" >
            <key>
                <column name="usersId" not-null="true" />
            </key>
            <one-to-many class="com.f0802.friend.entity.Messages" />
        </set>
        <set name="friendsForUsersId" inverse="true" cascade="delete" >
            <key>
                <column name="usersId" not-null="true" />
            </key>
            <one-to-many class="com.f0802.friend.entity.Friend" />
        </set>
        <set name="friendsForFriendId" inverse="true" cascade="delete" >
            <key>
                <column name="friendId" not-null="true" />
            </key>
            <one-to-many class="com.f0802.friend.entity.Friend" />
        </set>
    </class>
</hibernate-mapping>

Answer 3

public class UsersBizImp extends HibernateDaoSupport implements UsersBiz { public void addUsers(Users users) {
this.getHibernateTemplate().save(users); }}

Answer 4

UsersBizImp  没这东西啊 

Answer 5

去UsersDaoImp的第11行找，错误在那儿

Answer 6

this.getHibernateTemplate()没有取到值吧

Answer 7

sessionFactory要注入UserBizImp啊 

Answer 8

另外，请问biz是取自哪个单词？

Answer 9

public void saveBookTest(){
Book book=new Book();
book.setBookAuthor("Eric");
book.setBookContent("ok");
book.setBookName("123456");
book.setBookIsbn("isbn");
book.setBookPages("12");
book.setBookPrice("12.2");
book.setBookPublish("cbs");
book.setBookPublishDate(new Date());
System.out.print(book.toString());
Catelog catlog=new Catelog();
    catlog.setCatelogName("cat1");
    catlog.getBookList().add(book);
     System.out.print(this.getSessionFactory().toString());
    // this.getHibernateTemplate().save(catlog);
    //    this.getHibernateTemplate().save(book); }  我这样也报空指针异常 请大家帮忙看看 O(∩_∩)O~

Answer 10

很明显了，this.getSessionFactory()取不到东西，找找配置的原因吧

Answer 11

UsersDaoImp.java:11行，很清晰了啊，去看看吧，debug也行。

Answer 12

没有获取到 UsersDaoImp 实例 ，查看你的配置文件